jaydeehess
Penultimate Amazing
I'm tutoring students in freshman algebra. Their midterm review packet asked students the answer to 5 times pi. They were convinced that writing "5 pi" was unacceptable - that their teacher wanted a decimal answer.
This bothers me, but I didn't want to contradict her. Other teachers covering the same material were looking for "5 pi."
In manufacturing, irrational numbers will be truncated, but in this unit students were also being asked to identify numbers as rational vs. irrational and it seemed they were getting a mixed message.
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My example above was just that, one example.
Another common , nonunderstanable use of calculator would be something like;
16x109/4x103
Without a calculator , one who understands simple math can see the answer is 4 million( 4x106 )
One can also see the number of keystrokes a calculator would require, and thus the increased opportunity for finger generated mistakes. Understanding the math involved here also makes it obvious that when someone writes the answers down as , for instance 5.2 x107 you know damn well they used a calculator and what button mistakes they made. My co-students were shocked and amazed when I not only told them their answer was wrong but exactly what they did wrong.
Fact is the instructor said, several times, that he would devise question that simply did not require a calculator in most instances, that he was fine with multiples of pi as well.
In circuit design if the desired value of a resistor is calculated to be 400pi then a 1200 ohm resistor will suffice and if one needed more precision then add a 56 ohm resistor in series. One, he said, will not find a 1256 ohm resistor on the shelf. Rounding to the nearest standard value will likely be good enough.
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